diff --git a/reactos/subsystems/win32/win32k/ntuser/timer.c b/reactos/subsystems/win32/win32k/ntuser/timer.c
index 863987f689e..a1da2d64314 100644
--- a/reactos/subsystems/win32/win32k/ntuser/timer.c
+++ b/reactos/subsystems/win32/win32k/ntuser/timer.c
@@ -526,6 +526,8 @@ IntKillTimer(HWND Wnd, UINT_PTR IDEvent, BOOL SystemTimer)
       ASSERT(RtlAreBitsSet(&WindowLessTimersBitMap, IDEvent - 1, 1));
       RtlClearBits(&WindowLessTimersBitMap, IDEvent - 1, 1);
 
+      HintIndex = IDEvent - 1;
+
       IntUnlockWindowlessTimerBitmap();
    }